1. Field of the Invention
The present invention generally relates to image-processing apparatuses, image-processing systems, name registration methods, name registration programs, and record media, and particularly relates to an image-processing apparatus connected with a DNS server through a network, an image-processing system comprised of such image-processing apparatus, a name registration method for use in such image-processing apparatus, a name registration program corresponding to such a method, and a record medium having such program recorded therein.
2. Description of the Related Art
In the TCP/IP network environment, computers, network apparatuses, etc. connected to networks are uniquely identified by their IP addresses. Since IP addresses are nothing but a series of numerals, they are difficult for users to remember. In consideration of this, a system called DNS (Domain Name System) is employed, by which computers or the like are accessed by use of host names, which are character strings that are easier for users to handle.
In the DNS, DNS servers manage and control correspondences between host names and associated IP addresses. A DNS server resolves a host name in response to an inquiry from a client, and notifies the client of a corresponding IP address. As long as correspondences between the IP addresses assigned to computers or the like and the respective host names are correctly managed, proper name resolution by DNS servers is guaranteed.
IP addresses are generally assigned by a network administrator or the like. In each apparatus, a setup process must be performed to set an assigned IP address.
In order to reduce the user load for such work, to avoid a human error creating duplicate settings of the same IP address, and to facilitate effective use of IP addresses, DHCP servers are now used for the purpose of dynamically assigning IP addresses. DHCP servers can automatically assign IP addresses to individual apparatuses. Further, IP addresses assigned by the DHCP servers can be automatically set in apparatuses serving as clients associated with DHCP servers. This makes it possible to reduce the work load of network administrators and end users.
When a DHCP server is used in the DNS environment, however, a trouble may arise. As previously described, a DNS server manages correspondences between host names and associated IP addresses, and resolves names based on the correspondences. For such a DNS server, therefore, it is preferable to have static IP addresses, and the presence of a DHCP server that changes IP addresses dynamically contributes to the lowering of the reliability of the DNS server in terms of name resolution.
Against this background, the DDNS (Dynamic Domain Name System) has been developed as a technology for implementing the DNS also in the environment where IP addresses change dynamically. In the DDNS, each apparatus reports an IP address assigned by the DHCP server to the DNS server together with a hose name. With this provision, the DNS server keeps the latest correspondences all the time, thereby providing dynamic name resolution.
Moreover, Japanese Patent Application Publication No. 2000-101589 discloses a system that achieves a DDNS environment. This system provides for a DHCP server to report an IP address assigned to an apparatus to a DNS server, thereby keeping correspondences managed by the DNS server in the most recent status.
However, host names are also determined by humans in the DDNS environment. There is thus a possibility of a host name being mistakenly set to the same name as another apparatus.
FIG. 1 is an illustrative drawing for showing an example in which duplicate hose names are set. A system 500 of FIG. 1 includes a printer 510, a DHCP server 520, a client PC 530, a client PC 540, and a DNS server 550. The client PCs 530 and 540 are terminals such as PCs (personal computers) or the like for direct use by users. The client PC 530 has the IP address “192.168.1.4” and the host name “client.abc.co.jp”, and the client PC 540 has the IP address “192.168.1.3” and the host name “hostname.abc.co.jp”. Correspondences between the IP addresses and the host names are managed in the DNS server 550.
With respect to the printer 510, for example, the same host name (“hostname.abc.co.jp”) as the client PC 540 is set by mistake (S1). The printer 510 requests the DNS server 550 to register the correspondence between the newly set host name and the associated IP address (S2). In response, the DNS server 550 registers the correspondence between the host name “hostname.abc.co.jp” and the IP address “192.168.1.2” as a new entry.
Learning that the host name of the printer 510 is set to “hostname.abc.co.jp”, a user makes a setting such that the client PC 530 identifies the printer 510 as “hostname.abc.co.jp”. When the user gives a print instruction to print document data to the printer 510, the client PC 530 requests the DNS server 550 to resolve the name “hostname.abc.co.jp” (S3).
The DNS server 550 attempts to resolve the name “hostname.abc.co.jp”. Since there are two registered records indicative of the host name “hostname.abc.co.jp”, the DNS server 550 may mistakenly return the IP address of the client PC 540 to the client PC 530 (S4).
In this case, the client PC 530 issues a print request to the client PC 540 rather than to the printer 510 as originally intended, resulting in a failure to perform the printing of document data.
The same argument applies not only when there are duplicate host names but also when the host name of the printer 510 is changed without the knowledge of other users. In such a case, the client PC 530 tries to access the printer 510 by use of the host name before the change. Since the DNS server 550 manages correspondences based on the latest host names at all times, name resolution may not be performed correctly.
Accordingly, there is a need for an image-processing apparatus, an image-processing system, a name registration method, a name registration program, and a record medium which provide a DNS server to perform proper name resolution even when a host name is changed or provided as a duplicate of the host name of another apparatus in the DDNS environment.